The Lung Cancer Study Group (LCSG) has determined that central nervous system, in particular brain, metastases account for approximately 25% of the first recurrences in Stage I lung cancer. OBFS is analyzing the LCSG data to determine the relationships of recurrence in the CNS to prognostic factors and the effect of treatment on recurrence. The outcome for patients with CNS metastases will be investigated also. A paper reporting the initial findings of CNS recurrences is in press.